Whisk egg white and 2 tablespoons plus 1 teaspoon mustard in small bowl. Sprinkle skin side of chicken with salt and pepper. Brush thickly with mustard glaze; sprinkle with some of remaining mustard seeds.

Place chicken, skin side down, on grill. Sprinkle chicken with salt and pepper; brush with glaze and sprinkle with remaining mustard seeds. Grill 5 minutes. Turn chicken. Grill until cooked through, about 5 minutes. Top with slaw and serve.